linux-kernel - Re: [PATCH] x86/uaccess: Zero the 8-byte get

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Message-ID: <CAHk-=wjx1qBON_8+N2Mte8=EtpVRHNa+JCxbBnJXGs3=wF0c0g@mail.gmail.com>
Date: Wed, 31 Jul 2024 09:24:28 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: David Gow <davidgow@...gle.com>
Cc: Kees Cook <kees@...nel.org>, Borislav Petkov <bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	Peter Zijlstra <peterz@...radead.org>, Andrew Morton <akpm@...ux-foundation.org>, 
	"H . Peter Anvin" <hpa@...or.com>, x86@...nel.org, kunit-dev@...glegroups.com, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/uaccess: Zero the 8-byte get_range case on failure

On Wed, 31 Jul 2024 at 00:31, David Gow <davidgow@...gle.com> wrote:
>
> Fixes: 8a2462df1547 ("x86/uaccess: Improve the 8-byte getuser() case")
> Signed-off-by: David Gow <davidgow@...gle.com>

Ack.

I'd have liked to minimize the #ifdef's in code, but yeah, this fix is
obviously needed.

My bad. My mental model these days is the 64-bit case, where the whole
'check_range' thing is about address masking tricks, not the actual
conditional. So I didn't think of the "access_ok fails" case at all.

               Linus